Delayed arming booster



f at a p 2 1957 s. s. PODNOS ETAL 2,807,211

DELAYED ARMING BOOSTER Filed July 19, 1954 INVENTORS, Egalim 5. Foch-ms y .Eltaxncm HQTahh-Jn United States Patent DELAYED ARMING BOOSTER Selim S. Podnos, Washington, D. C., and Braxton H. Tabb, Jr., Alexandria, Va., assignors to the United States of America as represented by the Secretary of the Army The invention described herein may be manufactured and used by or for the Government purposes, without thepayment to us of any royalty thereon.

This invention relates to a delayed arming booster assembly for projectile fuzes and more particularly to booster detonators of the spherical rotor type.

' An object of the invention is to provide a booster detonator or a projectile which may be fired from a gun in an unarmed position, but which will become armed after the projectile leaves the gun, the time of arming being controlled by the design of the spherical rotor and by means of centrifugally responsive safety locking pins. In response to projectile spin, these pins recede from their locking positions to free the rotor for precession into armed position, but not before their positively applied torque has 'angularly accelerated the rotor sufliciently to start its precession well towards armed position.

An additional object of the invention is the arrangement of an indicator recess and detaining recesses in the rotor in such a manner so that the armed position of the rotor is not dynamically disturbed during spin in armed flight of the projectile.

A further object of the invention is the provision of rotor positioning means whereby a certain amount of creep of the rotor brings it in contact with the positioning means which results in steadying the rotor in its armed position.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangement of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims 3.1

These and other objects, features and advantages of the invention will be described hereinafter in detail, reference being made to the accompanying drawing in which:

Figure 1 is a longitudinal section of a booster assembly in the nose of a projectile incorporating the invention and being shown in unarmed or safe position.

Figure 2 is an enlarged sectional view of a detached rotor housing assembly showing booster detonator in an armed position but before the rotor has begun to creep forward due to deceleration.

Figure 3 is a fragmentary view of the parts of Figure 2 showing the rotor in fully armed position.

Figure 4 is a cross sectional view of detached rotor housing assembly taken along the line 4-4 of Figure 1.

Referring now more particularly to Figure 1, there is shown a projectile body 1 which is threaded at its nose portion as at 2 for the attachment thereto of a fuze assembly 3 of any suitable design. The fuze assembly contains a flash passage 4 for super-quick fuze action and parallel thereto is a second radially olfset flash passage 5 for delayed fuze action.

Positioned in the rear of the fuze body assembly and surrounding the flash passages is an annular channel 6 which is threaded as at 7. Threaded into this channel is the forward portion of an exteriorly threaded cylindrical body 8. This body includes a first cylindrical forward passage 9 formed with a first seat 10, a second and intermediate passage 11 of reduced diameter threaded as at 12 and formed with a second seat 13, and a third rearward passage 14 of still further reduced diameter the central bottom area of which forms a hemispherical seat 15 forming the rim of a rearward opening 16 which contains a booster lead cup 17. Threaded on to the rearward portion of the body 8 and against. the rear of the fuze body 3 is a booster cup 18. It will be understood that the lead cup and the booster cup are loaded with explosive material in the usual manner for such parts.

Threaded down to the seat 13 in the second or inter mediate passage 11 is a cylindrical rotor retainer housing or body 19 which has a central recess defining an annular rim 20. In the forward face of the housing 19 are openings 21 for the reception of a spanner wrench which is employed, for threading the housing against the seat 13. Interiorly, the housing 19 has a cylindrical bore 22 extending from the rear end into the forward section of the housing and terminating in a hemispherical forward end wall 23. The rear end of the bore 22 mates with the bore 14 to form a continuous passage. Extending from the center of the hemispherical end to the forward end of the housing is a co-axial counterbore 24 of reduced diameter, which is forwardly and outwardly tapered as clearly disclosed at Figure 2. The bore 24 is co-axial with the flash passage 4. Surrounding the reduced end of the bore 24 and extending into the hemispherical portion of the bore 22 is a steadying means comprising a frusto conical annular rim 25, which is formed by peening or spinning or in any other suitable manner. Located within the cylindrical bore 22 is an essentially spherical rotor 26 having an axis of symmetry 27, Figure 3. This rotor includes a first cylindrical bore 28 formed with a forward first seat means comprising a counterbore 29, and a second and intermediate cylindrical bore 30 formed with a rearward second seat 31, and a third rearward bore 32. ,These bores are all coaxial of axis 27. Positioned in the second bore is a cylindrical detonator 42, which is loaded in the usual manner with detonating material. The detonator is held in a fixed position against the seat 31 by staking or peening as indicated in Figures 2 and 3. The radius of the sphere according to which the rotor is formed equals that of the seat 15 so that upon setback they have complementary engagement. 1 3 1 r 1 The angled or safety position of the spherical rotor is indicated in Figure 1 wherein the axis 27 of the rotor lies at an angle to the longitudinal axis of the shell such that the detonator is entirely out of communication with the booster whereby the projectile is rendered safe. In order to properly set the angle, a conical indicator recess 33 is provided in rotor 26. Thus when the rotor is applied to the seat 15 before assembly of the housing 19 in the body 8, the proper angular position of the axis of spin is determined by placing the indicator recess central with respect to the open end of the body 8, a suitable pointed tool for the purpose being engaged with the recess 33.

Detent means is provided for holding the rotor in its safety position, consisting of four recesses therein identified at 34, 35, 36, and 37, Figure 4, and with which cooperate four cylindrical detent pins 38. These pins are in a plane normal to the diameter through recess 33, and pass through radial openings 39 in the housing 19.

These pins have such a length that, in the safe position, that is when their inner ends are fully seated in the respective recesses 34, 35, 36 and 37, their radially outward ends protrude a short distance outwardly of the bottom of an annular groove or channel 41 formed in the periphery of housing 19. These pins are normally withheld from radial movement by the annular spring 40 which is positioned in channel .41. The spring 40 is split and its ends separated by a lug 42 Figure 4) having position. Centrifugal force of the material of the spring also contributes to its expansion under rotation. Operation is as follows: I

Prior to and uponloading the cartridge into a gun, the fun is safe, because the rotor-is positively locked in the position shown in Figure l, from which it is impossible to move-it'except by rapid spin about the axis of spin of the shell. ,Suflieient spin cannot occur except .upon firing. r r

Upon firing, both axial and.angular accelerations occur, maximum angular velocity beingattained as the shell leaves the barrel of the'gunf Initially the spin'of' the shell is applied as torque to the rotor 26 because of the interlocking action of the pins 38. As the projectile leaves the barrel the rate of spin is suificient 'to-move the detent pins38 outward by centrifugal force against the 1 reaction from the spring 40. i As these detent pins release, some torque application to the rotor will be continued by reason of set back of the rotor against the seat 15, which continues to applyfrictional torque. Since the density of the detonator material is less than the density of the rotor 26, the rotorprecesses into the positionwherein its maximum moment of' inertia is aligned with the axis of spin of the shell which of course is the position shown in Figure 2 whereinthe bore 28 is in line with the bore 24 and'the detonator 42 is in line with the flash passage 4. r

- As the shell passes through its trajectory, a small axial deceleration (due to external air fraction) sets in. This however does not affect the rotor which therefore creeps forward from the position shownin Figure 2 to the position shown in Figured. In the latter armed position the opening established by the bore 28 engages or fits 'over the rim 25. This constitutes a positioning and steadying means further assuring proper alignment of the rotor'in its armed position. When the shell strikes a target either the superquick fuse or the delayed action "fuse is activated-and the flash from this activation travels through the appropriate flash passage igniting the booster detonator. r r

The armed position of Figure 3 will be maintained throughout the trajectory until'impact. Should the rate of spin decrease before impact to an amount insufficient 4 to overcome the radially inward thrust of ring spring 41, the spring will again contract and force pins 38 radially inwardly. Since the rotor is now in the forward or fully armed position the ends of pins 38 will engage the rotor about as shown upon Figure 3 rearwardly of the equatorial plane'thereof normal to axis 27, and will thereby cam" or urge the rotoriforwardly to hold it in the fully armed position. The stated objects of the invention are thereby'aehieyed and other advantages results attained.-;.

'As many changes could be made in the aboye con structions'without departing fromv the scope of theinvention, it is intended that all matter contained in the above description or shown in the accompanying draw-1 ings shall be interpreted as illustrative and v not in a limiting sense. 7 We claim:

1.v An explosive projectile comprising a projectile body having a' rotorretaining housing therein, said housing rotor surrounding one end of said detonator, Qmeans nor-' mally holdingisaid'detonator at an angle to said flash passage and centrifugally releasable from said angled position response to projectiles'pin so that said rotor will precess to align said detonatorwith said passage annular steadying means on said forward wall surrounding the rearward limit of said flash passage and extending into the interior of said housing, creep of said rotor when centrifugallyi released causing mating engagement of said annular steadyi-ng means and said seat means to. thereby positively position saidroto'r in its armed position.

2. A projectileas set forth in claim '1 whe reinjsa id forward wall comprises a concave 'liemisphericalseat surrounding said annular steady-ing means and having a' radius of curvature slightly larger than the radius of said "rotor. 1a; a

3. A projectile'as set forth in .claim 2,;Whereiuls'aid f .annularsteadying means comprises a frustro conical annular rim and said seat means comprises acounterbore ontsaid rotor coaxial with said detonator."

"References Cited inthe tileof patent V UN ED sIATEsr TEuTs- I 2,626,568 7 Podnos er a1.' Ian. 23 :1953 

